<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .box {
            /*定义使用flex布局*/
            display: flex;
            /*垂直布局*/
            flex-direction: column;
            height: 2000px;
            width: 100vw;
            background-color: white;
        }

        .shang {
            flex: 7;
            background-color: coral;
            display: flex;
            flex-direction: row;

        }

        .zuo {
            flex: 7;
            background-color: coral;
        }

        .you {
            flex: 3;
            background-color: #2c3e50;
            display: flex;
            flex-direction: column;
        }

        .you div {
            flex: 1;
        }

        .you div:nth-child(1) {
            background-color: #2c3e50;
        }

        .you div:nth-child(2) {
            background-color: pink;
        }

        .xia {
            flex: 3;
            /*设置div滚动*/
            overflow: scroll;
        }
        .xia li{
            font-size: 20px;
            color: black;
            height: 100px;
        }
    </style>
</head>
<body>
<div class="box">
    <div class="shang">
        <div class="zuo">左边</div>
        <div class="you">
            <div>右上</div>
            <div>右xia</div>
        </div>
    </div>
    <div class="xia">
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
        <ul><li>aaaa</li></ul>
    </div>
</div>
</body>
</html>